Drainage device for treating wounds using a reduced pressure

ABSTRACT

A drainage device for the treatment of wounds using reduced pressure, includes (a) a gas-type wound-covering element, which is fastened cohesively at the skin surface around the region of the wound and forms a sealed wound space, remaining between the respective wound and the wound-covering element; (b) at least one drainage tube, which can be connected to a device generating reduced pressure and can be inserted into the wound space approximately parallel to the wound-covering element; and (c) at least one absorption body in the form of at least one layer of a textile section, which is interspersed with super-absorbing particles and enclosed in an envelope. Due to the size of the pores of the envelope, the absorbed wound secretions remain within the absorption body and underneath the wound-covering element until the absorption body is removed from the wound space. An air opening is provided for the wound-covering element.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a continuation-in-part of co-pending U.S.application Ser. No. 11/791,058 filed on Jul. 5, 2007, which is thenational stage of PCT/EP2005/011702, filed on Nov. 2, 2005, which claimsthe benefit of German application 20 2004 018 245.9, filed on Nov. 24,2004, the contents of all of the foregoing applications are herebyincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The invention relates to a drainage device for treating wounds using areduced pressure, comprising: a gas-tight wound-covering element, whichconsists of a sheet-like material and, when placed in contact with thebody of the patient, is fastened adhesively to the surface of the skinabout the region of the wound, forming a sealed, wound space remainingbetween the respective wound and the wound-covering element, and atleast one drainage tube, which can be connected to a means, such as avacuum pump, for producing the reduced pressure and can be insertedprone into the wound space approximately parallel to the wound-coveringelement and over which the materials in the wound space can beevacuated, and at least one absorption body, which is disposed in thewound space and absorbs the wound secretions.

A device of the type named above is known from the DE 195 17 699. Theknown device has a covering sheet for covering the wound flat andclosing it off air-tight, so that a wound space, into which an insert ofa foam material and a drainage hose, which is pulled into this insert,are inserted, is formed underneath the covering sheet in the region ofthe wound. With the help of the insert of foam material, the woundsecretions are to be withdrawn uniformly over the whole of the woundsurface. A collecting container with a vacuum pump for producing thereduced pressure is, in turn, connected to the drainage tube. The wholedevice is disposed of when the collecting container is filled with woundsecretion. The purpose of the disposable device is to pass the woundsecretions continuously through the drainage tube into the collectingcontainer.

U.S. Pat. No. 5,549,584 shows a device for vacuum treatments, whichconsists of a wound cover, a membrane pump, which is disposed at thesuction tube, and a pouch-like collector, which is connected downstreamfrom the membrane pump. A layer of material or a loose bed ofliquid-absorbing fibers, which rest on a perforated layer and underwhich a further adhesive layer, in turn, is placed, is disposedunderneath the wound covering. Furthermore, the fibers are covered by aliquid-permeable upper layer, which has several windows. Beneath eachwindow, there is a section of material, which is also permeable toliquids. The suction tube is connected with a connecting piece, which isdisposed above the wound cover, and does not have any direct contactwith the absorption material, which is located within the wound space.The device, so designed, seems complicated and expensive to produce.

The DE 299 53 373 C2 also discloses a device, which uses reducedpressure for the treatment of wounds and comprises a wound-coveringelement, a foam material insert underneath the wound-covering elementand at least one flexible conduit, which communicates with the pores ofthe foam material insert. In the DE 38 50 798 T2, a sterile,rectangular, yet rigid cassette, in which a surgical dressing isaccommodated, is shown. The lower edge of the cassette is fastened tothe skin of the patient. For enclosing the surgical field at thepatient, the cassette is open at the top and at the bottom.

U.S. Pat. No. 5,086,763 A discloses a cassette-like wound-treatingdevice, which is also fastened to the skin of the patient. Anexchangeable wound dressing is placed at the underside of a swivelinglid.

A pouch-like wound-treating and wound drainage device, known from AT E33446 B, has a lower, peripheral edge, by which it may be glued to theskin of a patient, a catheter holder, two treatment openings with caps,which are disposed at an upper wall, as well as an opening at the lowerwall of the pouch for enabling access to the wound. The publicationdescribes only the construction of the pouch.

SUMMARY OF THE INVENTION

It is an object of the invention to design a cost-effective device forthe vacuum treatment of wounds, the design of which is simplified.

This objective is accomplished by a device of the type named above, forwhich the absorption body is at least one textile section, in whichsuper-absorbing particles are interspersed and which is enclosed in anenvelope, the envelope being permeable to liquids and having pores, thesize of which essentially does not exceed that of the super-absorbingparticles, the absorption body, which is to be inserted in the woundspace, having an initial volume, which enlarges in the course of theabsorption process and assumes a final volume, so that the absorbedwound secretions, due to the size of the pores of the envelope, remainwithin the absorption body and, with that, below the wound-coveringelement until the absorption body is removed from the wound space.

The wound-covering element may be fastened over a flexible connectingplate, the so-called base plate, to the body of the patient. One or moreopenings, which are fitted to the wound area(s), are cut from the baseplate before it is glued to the skin. It is, however, possible to dowithout the base plate, if a peripheral adhesive surface is applied,provided that the adhesive substance is harmless and an appropriateconnection site for introducing the drainage hose is provided at thewound-covering element. However, a conventional commercial wound-repairpouch with a gas-tight treatment window and a drain, the side wall ofwhich, opposite to the wound-covering element, is glued to theconnection plate at the factory, is preferred.

It is important that at least one absorption body, which is enrichedwith super-absorbents and can be exchanged, and one drainage hose, whichrests on the absorption body, are disposed within the wound-repairpouch.

The drainage tube may, however, also lie between two absorption bodies,which have the same or a different suction force and form a sandwicharrangement. For the sandwich arrangement, an absorption body, enrichedwith super-absorbents, and an additional absorption body, which is notprovided with super-absorbents, such as a flat, open-pored foam body,may be used. Different possibilities are provided here, namely, asandwich arrangement, for which the foam body lies between theconnecting plate and the absorption body, enriched withsuper-absorbents, or between the wound-covering element and theabsorption body, which is enriched with super-absorbents.

An optimum wound-healing process can be “programmed” by the selection ofabsorption bodies and their suction force.

The enveloped absorption body and/or the additional and/or theadditional foam-like absorption body and/or the adhesive film elementmay be provided with silver-, copper- or zinc-containing substances, forexample, in nanocrystalline form, in order to kill germs.

Without restricting the scope of the present invention, the term “superabsorbents” as used herein, includes, but is not limited to:

-   -   polyacrylates, particularly sodium polyacrylates and copolymers        thereof, including those in crosslinked form;    -   derivatives of cellulose, which for example may include, but are        not limited to, (a) sulfoalkylated celluloses and derivatives,        including cellulose ethyl sulfonate; (b) carboxyalkylated        cellulose, for example carboxymethyl cellulose, carboxyethyl        cellulose and/or carboxypropyl cellulose; (c) more complex        derivatives of cellulose, for example sulphoethyl carboxymethyl        cellulose, carboxymethyl hydroxyethyl cellulose,        hydroxy-propyl-methyl cellulose, and the like; and/or (d)        amidated derivatives of cellulose, for example carboxymethyl        cellulose amide or carboxypropyl cellulose amide;    -   alginates;    -   hydrogel nanoparticles including hydroxy-terminated methacrylate        monomers, for example 2-hydroxyethylmethacrylate (HEMA) and/or        2-hydroxypropylmethacrylate (HPMA), marketed, e.g., as        Altrazeal™; and    -   mixtures thereof.

All these materials can be used in form of fibers, particles, yarns,sponges, textiles, sheets and/or beads.

In some embodiments, the absorption body 2 may also contain compoundsfor the modulation of proteases, for example collagenases, elastases andmatrix metal proteases (MMPs). Without restricting the scope of thepresent invention, such compounds may be selected from, but are notlimited to, the group consisting of collagen, super absorbent polymers,or specific protease inhibitors.

In some embodiments, the absorption body 2 may also contain compoundsfor inducing hemostasis (arrest of bleeding). Without restricting thescope of the present invention, such compounds may be selected from, butare not limited to, the group consisting of gelatine, collagen, oxidizedregenerated celluloses, and pharmaceutical hemostatics.

In some embodiments, the absorption body 2 may also containantimicrobial compounds. Without restricting the scope of the presentinvention, such compounds may be selected from, but are not limited to,the group consisting silver or silver ions, octenidin, iodine-basedcompounds, bacteriostatics, chlorine-based compounds, primary andsecondary quorum sensing inhibitors, polyhexamethylene biguanide (PHMB),di-alkyl carbamoyl chloride (DACC), and lysing agents forexopolysaccharides.

It is also important that the area of the textile section of theabsorption body, enriched with super-absorbent particles, issignificantly smaller that that of the envelope, so that the absorptionbody, without being impeded in its cross section, can approach acircular form. The full utilization of the maximum or almost maximumfilling capacity of the absorption body contributes to lowering thecosts of treating the wound.

The wound-covering element may be transparent at least over a portion ofits surface, so that the state of the wound-healing process may beobserved. The drainage device may be provided with a liquid permeable,mucous membrane compatible protective element, which is disposed on aside of the absorption body, opposite to the wound-covering element andthe surface area of which is approximately equal to that of theenveloped absorption body. The protective element may also be producedfrom a soft, open cell foam material or a very loose nonwoven fabric.Finally, the protective element may also be a loose bed of pieces of anonwoven material or of a foam underneath the absorption body. At theend of the absorption process, these pieces are removed from the wound,for example with forceps. Moreover, a voluminous formation fulfills notonly the function of protecting the mucous membrane, but also that of anabsorber. The open cell foam or the nonwoven material may have pores,which are several times larger than those of the envelope, so that thelarger particles of wound exudate may be taken up.

If the device is glued to the body of the patient, the reduced pressurein the wound space beneath the wound-covering element can be producedmanually or mechanically or electrically. A most simple manualproduction of vacuum can be brought about, for example, with the help ofa so called scissors grip vacuum pump or a known rubber bellows (“ballpump”), which can be compressed by hand. Different conventional,commercial vacuum pumps, which can be supplied, for example, togetherwith a tube and a pressure regulator, are suitable for producing avacuum electrically.

For an in-patient, for example, post-operative treatment of a wound, thereduced pressure can be produced by connecting the drainage device to anexisting, stationary vacuum installation, optionally by way of apressure regulator.

In a plan view of its flat side, the device may be polygonal, oval orcircular or it may also be pouch-shaped, similar to the knownwound-repair pouches.

The envelope consists of a liquid-permeable, mucous membrane-compatiblenatural material or plastic, to which the wound secretions adherehardly, if at all. This enables liquid wound secretions to betransported into the absorption material. The wound secretions passthrough the envelope and are absorbed by the absorption material, whichhas been enriched with super-absorbents.

Advantageously, a peripheral overhang of envelope material is providedat the envelope of the absorption body, so that any painful contact ofthe relative hard seam with the surface of the wound can be limited oreven avoided. The envelope material a peripheral seam and the outerextent of the envelope is understood to be the overhang here.

The envelope of the absorption body many be provided with pulling means,so that the consumed, swollen absorption body can be pulled more easilyout of the wound region.

The envelope, as well as the absorption material within the envelope maybe provided with an odor-inhibiting and/or odor-neutralizing orodor-masking additive, such as activated charcoal.

It is of great advantage that, during the evacuation of the gases, woundsecretion particles are not carried along. These remain within theenvelope of the absorption body until the whole device is removed fromthe body of the patient and disposed of or until the swollen absorptionbody is exchanged. Overall, a device is created for the treatment ofwounds using a reduced pressure, for which the wound secretions areaspirated by the nonwoven material of the absorption body, which isinterspersed with super absorber, and remain within the envelopesurrounding the absorption body without getting back from the envelopeinto the covered wound space. As the absorption increases, the crosssectional area of the absorption body increases greatly by a multipleand approaches a circular shape. Essentially, no wound secretions arecarried along while the reduced pressure is being maintained with thehelp of a vacuum pump, which can be connected to the device, that is,when evacuating gases. Moreover, it is possible to do without anadditional collecting container. If an excess of wound secretion is tobe drained off, it is advisable to connect the drainage tube over acheck valve to a collecting container, which, in turn, is connectedupstream from a vacuum pump with a pressure manometer. In this case, theexchangeable absorption body acts as an intermediate storage device forthe secretions emerging from the wound.

The inventive drainage device can also be used for compression therapy,for example, for the treatment of open legs.

For a full understanding of the present invention, reference should nowbe made to the following detailed description of the preferredembodiments of the invention as illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a drainage device in plan view of the wound-coveringelement.

FIGS. 2 a to 2 d show the device of FIG. 1, glued to the skin of thepatient, in a diagrammatic section.

FIG. 3 shows the device of FIG. 1, however with a neck, also in planview of its flat side.

FIGS. 4 a to 4 c show a section A-A of FIG. 3 with three differentsandwich arrangements of two absorption bodies.

FIG. 5 shows the device of FIG. 1 or 3 in a diagrammatic longitudinalsection, connected to a portable or a stationary vacuum installation.

FIG. 6 a shows a further embodiment of the drainage device in plan viewof the wound-covering element.

FIG. 6 b shows a section, similar to that of FIG. 6 a.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be describedwith reference to FIGS. 1-6 of the drawings. Identical elements in thefigures are designated with the same reference numerals.

FIGS. 1 and 2 a to 2 d show a drainage device 100 for the treatment ofwounds using a reduced pressure is shown, comprising a rectangular and asheet-like, transparent wound-covering 3, a connecting plate 10 of ahydrocolloidlike material, between which there is an absorption body 2,and a drainage tube 4. An opening 11 (compare FIG. 2 a), the size ofwhich corresponds to that of the wound, is cut out of the connectingplate 10, so that, when the device 100 is glued to the skin of thepatient, a gas-tight wound space 5 results in the region of the wound(compare FIG. 2 b). A peripheral edge 25 of the wound-covering element 3is glued firmly to the connecting plate 10.

The gas-tight wound space 5 is thus bounded by the wound surface, thewound covering element 3 and the inner edge of the opening 11 at theconnecting plate. This wound space has a variable volume, since thewound-covering element 3 is not tensioned. The wound space, if it isconsidered as a reduced pressure space, also includes the interior ofthe drainage tube 4 up to the obstruction element, such as the checkvalve 17, shown diagrammatically in FIG. 5.

The drainage tube 4 is pushed over an envelope piece 22, which isdisposed at the edge of the wound-covering element 3, and under thewound covering element and rests on the absorption body 2, withoutcontacting the wound surface.

Furthermore, at each of its two flat sides, the connecting plate 10 hasa protective film 19, 24, of, which the protective film 19, facing thelater wound region, can be pulled off. The other protective film 24 isfinished to be adhesive on the side facing the wound-covering element 3.

The absorption body 2 is a layer 7 (compare FIG. 2 a) of a textilesection 33, which is enriched with super-absorbents and surrounded bythe liquid-permeable envelope 6. The envelope 6 has a peripheraloverhang 9 of material at its periphery, the area of the layer 7 beingabout 40% smaller than that of the envelope 11.

A drainage device 200, similar to the one described above, is sharing inFIGS. 3 and 5. For this drainage device 200, the wound covering element3 is part of a known wound-repair pouch 13 with a neck 27, the side wall8 (compare FIG. 5) of which, opposite the wound-covering element 3, isglued rigidly to the hydrocolloidal connecting plate 10, an outline 26of the wound-repair pouch, placed flat, protruding beyond the connectingplate. The flat absorption body 2 is accommodated in the interior of thewound-repair pouch 13, which is glued to the skin of the patient. Thewound contour 28 is outlined with a line 28 of dashes.

FIG. 4 a shows the drainage device 200 in the section A-A of FIG. 3. Asandwich arrangement 20 of two absorption bodies 2.1, 2.2, between whichthe drainage tube 4 is located, is a special feature of this embodiment.FIG. 4 b also shows a sandwich arrangement, for which an additionalabsorption body 32, which is not provided with super-absorbents, islocated between the wound-covering element 3 and the absorption body 2,which is enriched with super-absorbents. In FIG. 4 c, once again asandwich arrangement is shown, for which the additional absorption body32 is located between the connecting plate 10 and the absorption body 2,which is enriched with super-absorbents. In the last two cases, thedrainage tube 4 is disposed between the absorption bodies 2; 32, whichdiffer from one another. The additional super-absorber-free absorptionbody 32 is present in the form of an open pore foam body.

A relatively wide, round treatment opening 12, through which theabsorption body 2 or the additional absorption body 32 can be placed inor removed from the wound space 5, is incorporated at the wound coveringelement 3. The treatment opening 12 can be closed off gas-tied with aswiveling lid 23. An air opening 34, which is disposed in the center ofthe swiveling lid 23 and with which the reduced pressure can beregulated and adjusted in such a manner, that there may be a draft ofair within the wound space during the suction process, is showndiagrammatically in FIG. 1. FIGS. 6 a and 6 b show a drainage device300, which is essentially similar to that shown in FIG. 1. Thedifference consists therein that the perforated part of the drainagetube 4 underneath the wound-covering element 3 is forked. A stablepressure distributor 40 results in this way, since the two branches41.1, 41.2 rest on the 15 absorption body 2 and press against areinforced rim 42 of the swiveling lid 23.

A different pressure distributor 43 is present in the form of a flat,open cell foam piece 44 (compare FIG. 4 c). The foam piece 44 is hardlycompressible and therefore retains its thickness, which defines arequired distance A between the wound-covering element 3 and theabsorption body 2.

In addition, a sterile, air-tight packaging (not shown) is provided forthe device.

Function (see FIGS. 2 a to 2 d and 5):

A deep wound 29 is covered completely by gluing the drainage device(100) of FIG. 1 to the skin of the patient. Previously, an opening 11was cut out of the connecting plate 10 and, after that, the protectivefilm 19, shown in FIG. 2 a, was removed, so that an adhesive surface 30at the underside of the connecting plate 10 is exposed.

To begin with, the mucous membrane-compatible, perforated, film-likeprotective element 1 and then the flat absorption body 2 together withthe envelope 6 were carefully placed through the treatment opening 12with sterilized forceps 16 (not shown) onto the surface of the wound.The absorption body 2 has an initial volume V1. The drainage tube 4 isthen pushed in over the envelope piece 22 and under the wound coveringelement 3 in such a manner that it rests on the envelope of theabsorption body 2 (see FIG. 2 b). By gluing the drainage device to theskin, a gas-tight wound space 5 is formed between the wound-coveringelement 3 and the surface of the wound.

A vacuum pump 15, which can be operated by hand and is equipped with apressure manometer 15 (see FIG. 5), is connected over a line 31 with thedrainage tube 4. Since the wound space 5 is sealed, the gases in thewound space 5 can be evacuated with the help of the vacuum pump 15. Thestate is shown in FIGS. 2 b and 5. A reduced pressure of about 100 mm Hgwas produced within the wound space 5 with the help of the vacuum pump15. A check valve 17, which permits the flow of gases and possibly ofliquid wound secretions only in the direction of a collection container16, which is connected upstream from the vacuum pump 16, is disposed inthe line 31 between the envelope piece 22 and the vacuum pump 14.

The wound secretions, emerging from the wound, reach the absorption body2 and bring about a compression underneath the wound-covering element 3.After the aspiration of wound secretions, the absorption body 2 assumesa final volume V2 (see FIGS. 2 c and 2 d). All wound secretions, whichhave emerged from the wound, are absorbed by the absorption body 2.Basically, the outside of the envelope 6 remains dry.

The consumed absorption body 2 and the protective element 1 are nowremoved carefully from the region of the wound by raising the pivotinglid 23 with the help of forceps (see FIG. 2 d). If required, a newabsorption body and a new protective element 1 can be placed on thewound. If the wounds discharge very heavily, there may be an excess ofwound secretion, which is passed over the drainage tube 4 to thecollecting container 16.

If the patient is to be subjected to an in-patient wound treatment, thereduced pressure can be produced in the wound space in the wound regionby an existing, clinical vacuum installation 21 (FIG. 5). For thispurpose, it is advisable to incorporate a pressure regulator 18, withwhich the reduced pressure range can be adjusted, in the line betweenthe drainage tube 4 and the vacuum installation 21.

There has thus been shown and described a novel drainage device fortreating wounds using a reduced pressure which fulfills all the objectsand advantages sought therefore. Many changes, modifications, variationsand other uses and applications of the subject invention will, however,become apparent to those skilled in the art after considering thisspecification and the accompanying drawings which disclose the preferredembodiments thereof. All such changes, modifications, variations andother uses and applications which do not depart from the spirit andscope of the invention are deemed to be covered by the invention, whichis to be limited only by the claims which follow.

1. Drainage device for the treatment of wounds using reduced pressure, comprising: (a) a gas-tight wound-covering element, which comprises a sheet-like material and, in the state placed in contact with the body of the patient, is fastened adhesively to the surface of the skin around the region of the wound and forms a sealed wound space between the respective wound and the wound-covering element, (b) at least one means for producing a reduced pressure, connected to a drainage tube, which can be inserted into the wound space approximately parallel to the wound-covering element, by means of which material in the wound space can be evacuated, and (c) at least one absorption body, which is disposed in the wound space and absorbs the wound secretions, wherein the absorption body has at least one layer, which is enclosed in an envelope, of a textile section interspersed with super-absorbing particles, the envelope being permeable to liquids and having pores, the size of which essentially does not exceed that of the super-absorbing particles, the absorption body, which is to be inserted in the wound space, has an initial volume (V1), which increases in the course of the absorption process and assumes a final volume (V2), so that, due to the pore size of the envelope, the absorbed wound secretions remain within the absorption body and, with that, underneath the wound-covering element until the absorption body is removed from the wound space.
 2. The drainage device of claim 1, wherein, in plan view of its flat side, the layer has an area, which is 3% to 90% smaller than that of the envelope, so that the absorption body can unimpededly approach a circular shape in cross section in the vicinity of its total filling capacity.
 3. The drainage device of claim 1, wherein the wound-covering element has a window-like treatment opening, through which the absorption body can be placed into and removed out of the wound space, it being possible to close off the treatment opening gas-tight with a lid.
 4. The drainage device of claim 3, wherein at least one air opening, with which the reduced pressure within the wound space can be regulated, is disposed in at least one of the wound-covering element and the lid.
 5. The drainage device of claim 1, wherein the textile section of the absorption body comprises a non-woven material of cellulose fibers.
 6. The drainage device of claim 1, further comprising a liquid-permeable mucous membrane-compatible protective element, which is disposed on a side of the absorption body, opposite to the wound covering element and is approximately equal in area to the enveloped absorption body.
 7. The device of claim 6, wherein the protective element is in the form of a sheet.
 8. The device of claim 6, wherein the protective element is a section of textile material.
 9. The device of claim 6, wherein the protective element consists of a foam material.
 10. The device of claim 6, wherein the protective element is a bed of pieces of nonwoven material or of foam, lying underneath the absorption body.
 11. The drainage device of claim 1, wherein the wound-covering element is transparent at least at a portion of its surface.
 12. The drainage device of claim 1, wherein the wound-covering element is fastened over a flexible connecting plate to the body of the patient, at least one opening being incorporated in the flexible connecting plate.
 13. The drainage device of claim 12, wherein the wound-covering element is part of a medical care pouch, the side wall of which, lying opposite the wound-covering element, is affixed at least partly to the connecting plate.
 14. The drainage device of claim 1, wherein the envelope of the absorption body is sealed by ultrasonic seams.
 15. The drainage device of claim 1, wherein the absorption body has an overhang of enveloping material at its periphery.
 16. The drainage device of claim 1, wherein the drainage tube is passed to a collecting container, which is connected upstream from a vacuum pump and a pressure manometer.
 17. The drainage device of claim 16, wherein the vacuum pump is driven by at least one of electrical and mechanical means.
 18. The drainage device of claim 1, wherein the drainage tube lies between two absorption bodies forming a sandwich arrangement.
 19. The drainage device of claim 18, wherein the sandwich arrangement has an absorption body, which is interspersed with super-absorbents, and at least one additional absorption body which is not provided with super-absorbents.
 20. The drainage device of claim 19, wherein the additional absorption body is an open pore foam body. 